Recovery of Nickel from Electroplating Wastewater Using Fluidized Bed Granulation Process(FBG)

• Main Authors: Yi-Jing Chen, 陳怡靜
• Other Authors: Ming-Chun Lu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/t4c38b

碩士 === 嘉南藥理大學 === 環境工程與科學系 === 103 === Electroplating industries generate wastewater that contains significant amount of heavy metals. The most common method to treat heavy metals in wastewater is chemical coagulation. However, the said treatment method produces large volume of sludge that subsequent processes and additional cost are needed on the operation. A relatively new method such as crystallization using fluidized bed reactor (FBR) is at growing interest as it lessen sludge production and increases the recovery of metals as solid crystals. Synthetic nickel-containing wastewater had been used in this study as the representative for heavy metals in electroplating industry. The effects of operating parameters such as molar ratio, pH and flow rate were investigated to find the optimum condition. Experimental results showed that jar test cannot accurately determine the optimum pH suitable in FBR. High hydraulic load in FBR increases crystals collisions that deform some of the crystals produced and that it would accumulate as part of the sludge in the reflux section signifying poorer metal removal than low hydraulic loading. Using different concentration, higher concentration of nickel-containing wastewater have higher removal rate than the lower concentration but excessive dosage will increase processing costs and it is not economically feasible. It was also found out in the experiment that crystal growth must be controlled within a certain size range. Larger crystals tend to have lower removal rate than smaller crystals because smaller particles are in greater number that provides larger surface area than bigger crystals. Chelating agents in the wastewater prevents crystal formation that it should be treated first before introducing into the fluidized bed reactor. The crystals produced in the experiment underwent structural elemental analysis and the main product was determined to be nickel. Through SEM observation of the surface structure of a two hundred-nanometer colloidal particulate levels were grouped together to form dense crystalline beads.